HEADS UP - HAMMER work

Michael Neumann mneumann at ntecs.de
Sat Nov 15 12:51:38 PST 2008


Dennis Melentyev schrieb:
2008/11/15 Michael Neumann <mneumann at ntecs.de>:
Dennis Melentyev schrieb:
...
Sysctl/some-other-tunable with some kind of mask would be great for
fine-tuning (and just useless for the 90% of users).
like:
sysctl.hammer.dirhash.hashmask.prefix=1 (Starting at first filename
byte, 3 bytes fixed length)
sysctl.hammer.dirhash.hashmask.suffix=-1 (Starting last byte, 2 bytes
length)
Hm, but the hash is stored on-disk within each b-tree node, so changing the
hash-function becomes pretty dangerous!
That could be done via an option upon PFS creation, changed with
"hammer" utility parameter, whatever else way. As I wrote:
"sysctl/some-other-tunable".
Ah okay. A per-PFS setting would make sense to me.

Anyway, for me, it is fine tuning issue. Quite rare and very special
one. I hardly see any need in such thing for 99% of installations, but
there sure are cases when it is a huge plus.
That's why I'd prefer to just have one good heuristic which is in any 
way better than what UFS provides.

Regards,

  Michael





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